Cooler and humidifier for subsoil centrifuge



3,109,872 COOLER AND H-UMIDIFIER FOR susson. CENTRIFUGE Filed Aug. 29, 1961 l. S. M QUEEN Nov. 5, 1963 2 Sheets-Sheet 1 IATIIIIIIIIIIA=7IIJWIIM :VIIJ

INVENTOR [REL 5. MCQUEEN TTORNEYS TEMPERATURE (C Nov. 5, 1963 1. s. MCQUEEN 3,109,872

COOLER AND HUMIDIFIER FOR SUBSOIL CENTRIFUGE Filed Aug. 29. 1961 2 Sheets-Sheet 2 10 9:00 10:00 nioo l200 00 2:00 3= 0 TIM E (H 0 U R S) INVENT OR IRE]. 8. McOUEE/V M Ma BY Q

ATTORNEYS United States Patent 3,109,872 COOLER AND l-FJMEDQEER dUESQi-L CENTFF irel S. McQueen, Ar/ada, Coin, assiguor to the United States of America as represented by the Elecretary of the interior Filed Aug. 29, E61, tier. No. 134,735 4 Claims. till. Ediid) (Granted under Titie 35, U5. Code (2952), see. ass

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of royalties thereon or therefor.

The invention relates to improvements in a laboratory centrifuge apparatus useful in applying centrifugal forces to samples of soils or other materials wherein the maintenance of predetermined temperature and humidity conditions is critical. Apparatus according to the invention is particularly applicabl in determining the amount of moisture that will be retained in soil materials after drainage.

in a laboratory method using a centrifugal apparatus for determining the drainage characteristics of a soil, the resulting data indicating the quantity of water retained in the soil following draining, is expressed as the centrifuge moisture equivalent. More specifically defined, this equivalent is the water content retained by a soil that has been first saturated with water and then subjected to a force equal to 1000 times the force of gravity for one hour. For the details of this laboratory method, reference is made to the Standard Method for Test for Centrifuge Moisture Equivalent of Soils (D42539), in the 1958 Book of ASTM Standards, Part 4, page 1140-. However, the reliability of the results derived in the tests by the method noted, are often considered questionable due to the lack of reproducibility in such test results.

Extreme differences in results indicating the centrifuge moisture contents of soil samples were found between tests made according to the aforementioned method, and other tests which were distinguished by being conducted under conditions of a controlled temperature of 20 C., and a nearly constant relative humidity of 100% In the uncontrolled-temperature tests, samples were centrifuged for each hour during a seven hour period. In the controlled-temperature tests, samples were centrifuged for one hour during the first, third, fifth and seventh hours, and the centrifuge being run empty during the other hours. A continuous record of the temperature and relative humidity ranged from 98 to 100 percent in the controlledtemperature tests throughout the period of centrifuging. The relative humidity in the uncontrolled-temperature tests was close to 100 percent in the early minutes of centrifuging and then decreased to the humidity of the room which ranged from 32 to 34 percent. During the first hours of centrifuge operation, the humidity in the centrifuge reached room humidity Within one-half hour. During the succeeding periods the relative humidity in the centrifuge decreased from a high humidity to room humidity in less than five minutes. The temperature in the uncontrolledtemperature tests was initially 27.8 C., and progressively increased during succeeding hours of operation to about 46.7 C. after the seventh hour.

Centrifuge moisture content, as obtained in the uncontrolled-temperature centrifuge, decreased as the length of time of centrifuge operation was increased. In one test the measured moisture content after the centrifuge had Ce 3,1 $9,332 Fn'tented Nov. 5, l 963 been in operation for seven hours, was approximately onefifth of the value obtained after the centrifuge had been in operation for only one hour. Centrifuge moisture contents obtained in the controlled-temperature centrifuge were significantly different from those obtained in the uncontrolled-temperature centrifuge. The length of time the controlled-temperature centrifuge had been in operation had negligible influence on the centrifuge moisture contents of the same materials. It was concluded from these tests that the difficulty of obtaining good reproducibility of results for samples run in the uncontrolled-temperature centrifuge is primarily due to the progressive heating of the centrifuge as the length of period of operation is increased, as well as the lack of humidity control in the centrifuge.

Controlled-temperature centrifuging was obtained for the previously described, in a special type centrifuge enclosed in a refrigerated cabinet. Water placed in the bottom of the chamber of this centrifuge, provided a high humidity during the tests. It is therefore an object of the present invention to provide for use with existing standard centrifuges, a relatively inexpensive apparatus which is operable to maintain the temperature within the centrifuge below ambient or room temperature, and the relative humidity of the air Within the centrifuge sufiiciently high for allowing reproducibility of tests therein. Consequently, the present invention would permit the continued use of standard soil centrifuges, and avoid the need for replacin such standard soil centrifuges with expensive refrigerated centrifuges.

It is a further object of the present invention to provide an apparatus easily and conveniently fitted to the structure of a standard soil centrifuge, and adaptable to function therein to improve the operation thereof.

A still further object of the present invention is to provide for use in conjunction with a standard soil centrifuge, an apparatus for adding moisture to the atmosphere of the chamber of the centrifuge, in a manner such as to maintain a relatively low uniform temperature and a high relative humidity.

These and other objects and advantages of the invention will be more clearly understood from the following description of a preferred embodiment of the invention, considered together with the accompanying drawing wherein:

FIG. 1 is a vertical cross-sectional view of a portion of the centrifuge revealing the improved apparatus in place thereon;

FIG. 2 is a vertical sectional view of the improved apparatus, on line 22 of FIG. 1;

FIG. 3 is a plan view partly in section, of the apparatus, showing a horizontal section of an internal element on line 3-3 of FIG. 2; and

FIG. 4 shows graphical representations of data derived while conducting moisture equivalent tests in a centrifuge operated under various conditions of moisture control.

Referring to FIG. 1, a part of a standard centrifuge 1 is shown wherein the present invention is aifixed to an existing vent or drain hole 2, usually provided through the bottom section of the guard bowl 3, constituting the upper outer portion of the centrifuge. Also shown is a spray nozzle 12 of the apparatus, directed to spray tangentially to the path in which draining chambers (one of which is shown), are rotated by means of a rotatable support arm 5, within the confines of the guard bowl 3. Mounted in an upper bearing chamber 6 of the centrifuge, is a motor driven shaft 7 to which is fastened the support anm 5. Secured together by conventional bolts to form the over-all centrifuge structure, are the bearing chamber d, a motor mounting plate 8, and the centrifuge base 9, containing a variable speed electric motor (not shown).

in FIGS. 2 and 3, the standard centrifuge is shown only by a fragmentmy portion it"? of the fixed guard bowl 3, representing the bottom of the bowl. Fitted into opening 2 in the bottom of the centrifuge bowl, is the upper rim of a relatively wide collar like tube 2% of acrylic material. The outside diameter of this tube is substantially equal to the diameter of the drain opening to allow a press fit between tube and bottom 1%. Through tube 29 is inserted a tube 22, also of acrylic material, having a portion 23 contacting and attached by screws, to an inner wall surface of tube Eli, and filling thereby about two-thirds of an opening 21, in tube Extending from the portion 23 of the inner tube 22, to be above and below tube 24 are further its portions 24 and 2 5, respectively. Upper portion 24 is in the form of an elbow having an arm at right angles to portion 23, and providing by its open end '26, an outlet from the tube 22, concentric with nozzle 12, and facing the inner vertical wall of the centrifuge bowl 3. Lower portion 25 extending straight downward from portion 23, for a distance equal to about the Width of tube 2%, provides by its outer surface a support for a cup-like drainage separator 35. In the bottom of separator is a relatively large opening 31, having a relatively wide and tapering interior collar, the inner rim of which fits snugly over the end portion 25 of the tube 22, and which rests on a rubber ring 34 on portion 25, to efi'ect the support and a seal for the separator. A second smaller hole in the separator bottom, opens into a drain tube 32 extending downward for connection to a floor drain or a storage vessel. Cylindrical wall 33 of the separator Sil :by extending vertically around and a short distance above the lower opening of tube 2%, provides an enclosure for this opening.

A relatively small diameter conduit tube if? of acrylic material, secured within tube 22, by being cemented to the inner surface thereof, is curved to form an elbow at its upper end to follow the conduit passage of tube 22'. This curved part of tube so, which follows the horizontal section of upper portion 24, is axially positioned within the portion. Secured at this end of tube iii, by means of a Tygon tubing sleeve 42, the spray nozzle 12 extend ing through, and slightly beyond the opening 26 in tube 22. A suitable nozzle 12 is provided by a conventional water spray head of brass soldered to a short length of copper tubing. Within the centrifuge and supported on the inner surface of the bowl bottom lb, is an open ended cap-like venturi air scoop structure covering over by its flat top 51, and converging vertical sides 52, 53, the opening in tube 2i and the upper portion 24 of tube 22 to which the top is fastened by screws. The wide opening in end 54 of the scoop is located directly over the unfilled part of tube 2%, and the narrower part 55 of the scoop, is positioned to overlie the tube opening 26, and to define passages so, -7, on either side of the upper portion 24.

The apparatus according to the invention provides a means of introducing dry air and avater into the guard bowl of the standard subsoil centrifuge so that the water in mixing with the air, evaporates to draw heat from, and consequently cool the environment of the centrifuge guard bowl. High velocity circulation of the air within the centrifuge guard bowl produced by the operation centrifuge apparatus, presses air into the wide open end 54. of the venturi air scoop The additional velocity imparted to the air as it passes through the converging section of the air scoop and out from its passages so, 57, creates a turbulence around the opening 26 in tube portion 24. Water is metered into the tube to come out as a fine spray from nozzle 32. Air from outside the centrifuge apparatus is drawn up through tube 23, and is caught in the turbulence around opening The line spray from the nozzle 12 enters directly into the zone of high turbulence where there is a lr'ghly effective mixing of Water and air, and evaporation of the water particles sprayed. the centrifuge guard bowl impinges against the outside of tube 22, and is carried by the air flowing out through the opening 21 in tube 21?, to the inner surface of separator drainage cup 3b. This air leaving the centrifuge guard bowl passes out to the atmosphere through the open top of the separator. The excess water collects within the separator and drains out through pipe 32, to the floor drain or storage vessel for subsequent disposal or recirculation.

By referring to the graphical material of PEG. 4, there will become evident the efiicaciousncss of the improved apparatus of the present nvention. The four curves and other data shown in the figure, relate to operating conditions in the centrifuge during hour long centrifuge moisture equivalent tests made in the six hours of a normal days ope-ration. Curve A represents temperatures in degrees centigrade, measured in the guard bowl 3 of a standard centrifuge operating without the apparatus of the present invention. Curve B represents temperatures similarly measured, but with the improved apparatus in place and being used in the centrifuge guard bowl during the greater part of the days operation. Along the remaining two curves C and D, are to be found the dry bulb and wet bulb temperatures, respectively, of the outlet air from the centrifuge guard bowl wherein the improved apparatus is also in place, and in use during the greater part of a days operation. FIG. 4 additionally provides data as to the relative humidity of the outlet air corresponding to the temperatures indicated at each of several different points along curves C and D. Temperatures for the curves A and B were measured in the guard bowl 3 of the centrifuge with a copper-constantan therrnocouple, and were recorded. Wet and dry bulb temperatures of the air leaving the centrifuge were measured with thermocouples installed for this purpose in the separator cup 3% Considering first the curve A, it can be seen that after the start of each hourly test run in a standard centrifuge not equipped with the improved apparatus, a significant temperature rise occurred so as to pass beyond points A on the curve. It was only after the incomplete cooling allowed during periods when the centrifuge lid was opened between runs, that any drop in temperature is noted as at points A on the curve. However, another glance at curve A shows that after the start of operations, the tel peratures did not drop below the ambient or room temerature indicated in FIG. 4, by the broken line X.

When the moisture cooling apparatus provided in accordance with the present invention is made operative in the centrifuge, the temperatures measured in the bowl 3 and separator 38, are as indicated by curves B and C, D, respectively, between the time scale points 9:00 and 10:00, and between scale points 11:45 and a little beyond 3 :60, maintained significantly below room temperature. Between scale points 10:90 and 11:45, the pressure regulated water supply to tube 4% was cut oil, and a corresponding rapid rise in temperature is evident on curves B and C, whereas a sharp decline in wet bulb temperatures is shown by curve D. The indicated relative humidities based on curves C and D also clearly show the highly effective control of air conditions in an operating centrifuge, which may be had by means of the unique apparatus of the present invention. It should also be understood that the relative humidity of the air within the centrifuge is actually higher than that of the outlet air indicated in FIG. 4. This is due to the mixing of the outlet air with outside air ahead of the point of measurement in the separator. In any case, the relative humidity inside of the centrifuge should be very near to percent because of the excess of water in the guard bowl.

The table below lists data for four different soil ma Excess water in the air circulating around terials tested for their centrifuge moisture equivalents (CME), in a standard centrifuge in which the present invention was installed, and in a standard centrifuge not so equipped. In addition, the table lists the centrifuge moisture equivalents for these materials as reported from an extensive series of tests made in the special refrigerated centrifuge and by other moisture tension methods:

A comparison of the listed data further illustrates the unusual and unexpected effectiveness of the present invention to perfect the accuracy and reproducibility of centrifuge moisture equivalent tests made in a standard centrifuge. In the claims herein below, the terminology used therein may be read on the preferred embodiments as follows: tubular elements 29, 22 and 40 correspond to the first, second and third elements in the claims; passage 21 corresponds to the first open or air passage; the passages defined between the Wall of tubular elements 22 and 40 (including passage 26) corresponds to the second open or air passage in the claims; the passage defined between the wall of tubular element 29 and cylindrical cup 33 corresponds to the third open passage.

While a preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited thereby, but is susceptible of changes in form and detail without departing from the spirit of the invention as defined by the appended claims.

I claim:

1. In a centrifuge apparatus cooperating with a source of water, the combination of a centrifuge guard bowl having a vent opening in the bottom thereof and an air conditioning apparatus comprising a plurality of tubular elements, a first of said tubular elements having an upper circumferential portion supported to fully encompass the said vent opening in the bottom of the guard bowl, a second of said tubular elements secured Within the said first tubular element such that respective upper and lower parts of said second tubular element extend above and below the first tubular element, the inner and outer surfaces of the first and second tubular elements respectively, defining a first outlet passage from inside the guard bowl, a third of said tubular elements secured within said second tubular element such that the inner and outer surfaces of the second and third tubular elements respectively, define a second open passage from the atmosphere to inside the guard bowl, said third tubular element having a conneciton to the said source of water at one end, and a spray nozzle at its other end extending out from an opening in said upper part of the second tubular element, a cup means and further means to support and seal said cup means to the said lower part of the second tubular element, said first tubular element extending down from the centrifuge guard bowl vent opening and into the cup means such that the inner and outer surfaces of the cup means and the firts tubular element respectively, define a third open passage which joins said first open passage to complete an open path from inside the guard bowl to the atmosphere, and a converging inverted channel member supported within the guard bowl, having an upper surface spanning the said first passage, and the said upper part of the second tubular element, and side surfaces converging from a relatively large cross-sectional area in the channel path adjacent said first passage to a relatively small crosssectional area in the channel path adjacent said opening in the upper part of the second tubular element.

2. In the centrifuge air conditioning apparatus of claim 1, said cup means being provided with a bottom having an opening therein, and a further tubular element secured in said bottom opening and connectible to a drain facility.

3. In a centrifuge apparatus cooperating with a source of Water, the combination of a centrifuge guard bowl in which parts rotatably driven cause air therein to circulate in streams, having a vent hole in the bottom thereof, and an air conditioning apparatus comprising a plurality of conduit elements, each having a different diameter and openly nested for mounting in the said vent hole of the centrifuge guard bowl, to provide a first air passage from inside the guard bowl to the outside thereof, and a second air passage leading from the atmosphere and opening inside the guard bowl, said second passage having fastened therein one of the said plurality of conduit elements having a connection to the said source of Water at one end thereof, and a spray nozzle at its other end directed towards the inside of the centrifuge guard bowl to distribute therein particles of water, and a converging air passage element supported wholly within the centrifuge guard bowl to partly enclose the conduit elements opening therein and effective for directing a portion of a stream of air circulating within the centrifuge guard bowl as it passes over the said first air passage, to the outside of said guard bowl, and causing turbulence of another portion of said stream of circulating air as it passes around the said opening of the second air passage whereby atmospheric air coming therethrough into the guard bowl, and particles of water from said spray nozzle are thoroughly mixed in said portion of turbulent air in said circulating air stream.

4. In the centrifuge air conditioning apparatus of claim 3, a water particle collector means having a fully open end and a drain connection in its opposite end, attached to the conduit providing the second air passage, and its fully open end being under the opening of the conduit providing the first air passage to outside the centrifuge bowl, and providing by means of its surface extending between the said ends, a third passage communicating with said first air outlet passage to direct the air output of the centrifuge bowl to the atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS 1,321,288 Dalzell Nov. 11, 1919 1,567,712 Cookson Dec. 29, 1925 1,658,533 Mart Feb. 7, 1928 2,878,992 Pickels et a1 Mar. 24, 1959 2,917,229 Benedetto et al. Dec. 15, 1959 FOREIGN PATENTS 290,745 Switzerland Aug. 17, 1953 

1. IN A CENTRIFUGE APPARATUS COOPERATING WITH A SOURCE OF WATER, THE COMBINATION OF A CENTRIFUGE GUARD BOWL HAVING A VENT OPENING INTHE BOTTOM THEREOF AND AN AIR CONDITIONING APPARATUS COMPRISING A PLURALITY OF TUBULAR ELEMENTS, A FIRST OF SAID TUBULAR ELEMETNS HAVING AN UPPER CIRCUMFERENTIAL PORTION SUPPORTED TO FULLY ENCOMPASS THE SAID VENT OPENING IN THE BOTTOM OF THE GUARD BOWL, A SECOND OF SAID TUBULAR ELEMENTS SECURED WITHIN THE SAID FIRST TUBULAR ELEMENT SUCH THAT RESPECTIVE UPPER AND LOWER PARTS OF SAID SECOND TUBULAR ELEMETN EXTEND ABOVE AND BELOW THE FIRST TUBULAR ELEMENT, THE INNER AND OUTER SURFACES OF THE FIRST AND SECOND TUBULAR ELEMENTS RESPECTIVELY, DEFINING A FIRST OUTLET PASSAGE FROM INSIDE THE GUARD BOWL, A THIRD OF SAID TUBULAR ELEMENTS SECURED WITHIN SAID SECOND TUBULAR ELEMENT SUCH THAT THE INNER AND OUTER SURFACES OF THE SECOND THA THIRD TUBULAR ELEMENTS RESPECTIVELY, DEFINE A SECOND OPEN PASSAGE FROM THE ATMOSPHERE TO INSIDE THE GUARD BOWL, SAID THIRD TUBULAR ELEMENT HAVING A CONNECTION TO THE SAID SOURCE OF WATER AT ONE END, AND A SPRAY NOZZLE AT ITS OTHER END EXTENDING OUT FROM AN OPENING IN SAID UPPER PART OF THE SECOND TUBULAR ELEMENT, A CUP MEANS AND FURTHER MEANS TO SUPPORT AND SEAL SAID CUP MEANS TO THE SAID LOWER PART OF THE SECOND TUBULAR ELEMENT, SAID FIRST TUBULAR ELEMENT EXTENDING DOWN FROM THE CENTRIFUGE GUARD BOWL VENT OPENING AND INTO THE CUP MEANS SUCH THAT THE INNER AND OUTER SURFACES OF THE CUP MEANS AND THE FIRTS TUBULAR ELEMENT RESPECTIVELY, DEFINE A THIRD OPEN PASSAGE WHICH JOINS SAID FIRST OPEN PASSAGE TO COMPLETE AN OPEN PATH FROM INSIDE THE GUARD BOWL TO THE ATMOSPHERE, AND A CONVERGING INVERTED CHANNEL MEMBER SUPPORTED WITHIN THE GUARD BOWL, HAVING AN UPPER SURFACE SPANNING THE SAID FIRST PASSAGE, AND THE SAID UPPER PART OF THE SECOND TUBULAR ELEMENT, AND SIDE SURFACES CONVERGING FROM A RELATIVELY LARGE CROSS-SECTIONAL AREA IN THE CHANNEL PATH ADJACENT SAID FIRST PASSAGE TO A RELATIVELY SMALL CROSSSECTIONAL AREA IN THE CHANNEL PATH ADJACENT SAID OPENING IN THE UPPER PART OF THE SECOND TUBULAR ELEMENT. 